A bed says what it actually needs to be pointed at

The instructions in every bed named the bundle that raises the predecessor's
broker, so a first attempt ends in a control plane crash-looping on a missing
MESH_BUS_NATS — which reads like a broken lab. They name the bundle that works
now, and the README says the host binary needs SYSTEM=arch, because one built
without it refuses everything with an empty system name.

And the three habits that each cost a run before they were adopted:
MESH_LAB_KEEP to leave the machine standing, MESH_LAB_WARM while iterating,
and rebuilding all three repositories the bed places rather than the one that
changed.

test/integration/assigned-catalogue-mqtt.test.ts

@@ -22,7 +22,7 @@
  * the seed), and mosquitto's provisioner — running in the assigned runtime — creates a scoped client
  * for a contribution the mesh delivered, which then authenticates with the password the mesh minted.
  *
- *   MESH_LAB_HOST_BINARY=.../mesh-host   MESH_LAB_BUNDLE=.../examples/foundation-first-node.lock
+ *   MESH_LAB_HOST_BINARY=.../mesh-host   MESH_LAB_BUNDLE=.../examples/foundation-first-node-nats.lock
  *   scripts/build-module-runtime.sh mosquitto builds mesh-runtime-mosquitto:development (carrying
  *   mosquitto_ctrl and the compiled bootstrap entrypoint) into the local daemon, which
  *   scenarios/catalogue-mqtt.yml stocks. eclipse-mosquitto:2 must be in the local daemon to be